1. Field of the Invention
The present invention relates to a semiconductor device, and particularly, to a semiconductor device including a circuit in which power supply is controlled by a switch circuit.
2. Description of Related Art
In recent years, in semiconductor devices, miniaturization of semiconductor elements such as transistors is in progress in order to realize high integration. However, because of the miniaturization of a transistor, a leak current in a transistor has significantly increased. In view of this, a switch circuit (e.g., switch transistor) is provided between a power source line and a transistor that forms a circuit, thereby reducing a leak current caused when the circuit is stopped. Such a method of controlling power is disclosed in Japanese Unexamined Patent Application Publication No. 2007-95787.
Japanese Unexamined Patent Application Publication No. 2007-95787 discloses a technique in which a switch transistor is provided between a lower-layer line connected to a circuit as a power control target and an upper-layer line that receives power supply from outside. In a case of stopping the circuit, a switch transistor is caused to be in an off state to bring the lower-layer line and the upper-layer line into a shutdown state, thereby reducing a leak current that flows into a transistor forming a circuit.